1. Field of the Invention
The present invention relates to a reduction mechanism for a gear motor or the like having high torque output and used in a muscle force assisting device or the like.
2. Description of the Related Art
Conventionally, a gear motor that has high torque output uses a multistage planetary gear system in which planetary gear mechanisms are stacked together in two stages and a reduction ratio is obtained.
However, in a system such as this, although high torque output can be achieved, there is a disadvantage in that size and weight reduction cannot be achieved.
Therefore, a compound planetary gear mechanism formed by the elements of two planetary gear mechanisms being joined in a planar manner is considered.
However, various conditions (such as geometric conditions, adjacency conditions, and assembly conditions) apply to the design of a planetary gear mechanism, thereby significantly limiting the degree of freedom in design thereof.
In particular, extremely strict restrictions are set by the assembly conditions for enabling all planetary gears to correctly mesh with a sun gear and an internal gear. There is a disadvantage in that the combinations of the numbers of teeth and the reduction ratio that can be selected are significantly limited.
[Patent Literature 1] Utility Model Publication No. S64-35237
[Patent Literature 2] Japanese Patent Publication No. 3248690